Black crystals of the very rare Mn-Sb-As oxide manganostilbite from the TL in Sweden (Brattfors Mine, Nordmark, Filipstad, Värmland County, Sweden). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Manganostibite
Manganostibite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Mn²⁺₇Sb⁵⁺As⁵⁺O₁₂.
It crystallizes in the orthorhombic crystal system (space group Ibmm). It is a member of the Manganostibite structural group.
Key properties: specific gravity 4.949; Chocolate-brown streak; Greasy luster; optically biaxial.
IMA symbol Mnsb, grandfathered status — known before the IMA’s founding, named in 1874.
Found in late-stage hydrothermal veins in manganese deposits in limestone.
It is found associated with Hausmannite, sonolite, katoptrite, manganoan humite, garnet.
The name refers to MANGANese and antimony, STIBium, in the composition.